It’s a task most people dread - filling out your annual tax return.

But with less than a month until the 31 January deadline for online tax returns, now is the time to get organised.

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Who needs to fill in a tax return?

If you run your own business, you’ll need to complete a tax return every financial year.

But it’s not only the self-employed who have to complete them. For example, you also need to fill in a return if you’re an employee who earned £100,000 or more in the past tax year.

If you know you need to do a self-assessment tax return, don’t wait for HMRC to chase you. It's your responsibility to make sure you declare taxable income each year to avoid fines.

Find out who needs to pay self-assessment tax.

How to file a self-assessment tax return

The deadline for this year’s paper tax returns has already passed, but you still have time to complete an online return. For the 2017-18 tax year, HMRC must receive your return before midnight on 31 January 2019.

The deadline for this year’s paper tax returns has already passed, but you can still fill in an online return.

For the 2018-19 tax year, HMRC must receive your return before midnight on 31 January 2020.

If you haven’t submitted an online tax return before

You’ll need to register with HMRC in advance. You’ll also have to wait for a UTR number and an activation code to arrive by post. This can take several days, so make sure you register in plenty of time before the deadline.

If you’ve used the service before

You can log in with your user ID to complete your return.

Need help? Use the jargon-free Which? tax calculator to work out your bill and submit your tax return directly to HMRC.

What happens if your tax return is late?

If you miss the 31 January deadline:

  • HMRC will fine you £100
  • in the first three months after the deadline, an extra £10 charge will be added each day (capped at 90 days).

Further fines can be added if you continue to miss deadlines, which could add hundreds or even thousands of pounds to your bill.

If you also fail to pay the tax you owe by 31 January, you’ll be charged interest from the date the payment was due.

Find out more about late tax returns and penalties.

Watch out for tax scams

HMRC is warning taxpayers to watch out for fraudsters in the run up the deadline.

Common scams include phoning people offering a fake tax refund, or pretending to be HMRC by texting or emailing a link which takes customers to a false page where their bank details and money will be stolen.

Genuine organisations such as HMRC will never contact you asking for you PIN, password or bank details. You should not give out private information, reply to text messages, download attachments or clink on links in emails which you aren't expecting.

If you receive any suspicious calls or emails claiming to be from HMRC, you can report them to You can forward any suspicious texts to 60599.

If you've lost money as a result of a scam, contact Action Fraud on 0300 123 2040 or use their online fraud reporting tool.

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